Electrical reproducing device



Aug. 16, 1938.

C. P. MITCHELL ELECTRICAL REPRODUC ING DEVICE Filed Feb. 12, 1937 INVENTOR.

WW1 K ATTORNEY-9 Patented Aug. 16, 1938 ELECTRICAL REPRODUCING DEVICE Curtis P. Mitchell, Springdale, Ohio, assignor to The Palmer Company, Cincinnati, Ohio, a corporation of Ohio Application February 12, 1937, Serial No. 125,384

Claims.

This invention relates to electrical apparatus and is particularly directed to an apparatus for electricallyreproducing motion at a location different from the location at which it is applied. More specifically, the invention is utilized as an electrically operated system for reproducing, recording, or showing temperatures at points removed from the environment, the temperature of which is being determined. The present invention may be considered in relationship to my previously issued Patent #2,036,091 issued March 31, 1936, disclosing and claiming'an electrical reproducing device for the same general purposes and uses as that herein disclosed.

It is an object of this invention to provide an apparatus or system for electrically reproducing thermostatically detected temperature changes by means of a unit placed at the environment of temperature change which may be a theatre, an oven, etc., and connected by electrical means to a receiving unit which may be located at a remote point such as the outside of the theatre or the recording room of a bakery or any extremely remote point. The receiving apparatus receives signals from the sending device by electrical control and converts them into mechanical movement which is efiective or temperature record or display purposes.

It is a further object of this invention to provide apparatus of this character which is extremely sensitive and which, therefore, transmits the very slightest change in temperature and immediately displays or records the change substantially simultaneously with the occurrence thereof. Moreover, it is arranged that, in the event of power failure, these devices will operate automatically when the power is restored for quickly and accurately reproducing the temperature reading existing at the time of power restoration without requiring manual resetting of the apparatus.

It is a more general object of this invention to provide a system and apparatus for electrically reproducing relative movement at a location remote from the location at which the motion is portions of the apparatus, particularly in the event that the receiving portion of the apparatus becomes inoperative or acts too rapidly or too slowly.

Other objects and certain advantages will be more fully apparent from a description of the accompanying drawing, in which:

The figure of the drawing is a diagram illus- -trating the electrical and mechanical elements of the apparatus and system and disclosing the electrical connections therebetween.

In the disclosed embodiment of the invention set forth in the above mentioned patent, a series wound commutator type of motor is used. Reversal is accomplished by splitting the field winding into two parts and making the connections so that each field serves for one direction of rotation. The transmitter and receiver portions of the apparatus are kept in synchronism by arranging the circuit so that, as the transmitter advances one step, the voltage in the transmitter is reduced to a point insufilcient for its operation by the operation of the receiver, and cannot proceed until the receiver has advanced one step.

The present invention employs small shaded pole induction type motors which have the advantage that they run at uniform speeds. The previous system of synchronizing control is not adapted to the induction type motor since the induction motor is more independent of line voltage. Accordingly, a different system of control and means of synchronizing has been adopted herein.

in detail) that if the receiving portion of the i apparatus fails to keep up with, or gets ahead of, the transmitting portion, or does not operate for some reason, the field winding of both motors on the transmitter will be energized at the same time. Since they are wired to run in opposite directions, the transmitter will stop instantly when this occurs. When, and if, the receiving end reaches the proper position, the normal connections are restored on the transmitting motors for operation in one or the other direction.

Referring to the drawing, the sending or transmitting unit is generally indicated at A, and the receiving unit at B. The disclosed embodiment of the invention is arranged for recording temperatures at a point away from the environment, the temperature of which is being determined. For example, the sending or transmitting unit may be located in the interior of a theatre and the receiving unit-at the exterior of the theatre, for disclosing to the public the temperature within the theatre. As another example, the sending, or transmitting, unit may be in an even of a bakery with the recording or receiving unit located in an executive's or manager's office, or in a control room, particularly where the bakery is a large institution.

The thermally sensitive or responsive element back and forth as the tube coils and uncoils due to temperature changes effecting the expansible liquid, as disclosed in the patent heretofore mentioned.

As illustrated, the swinging arm III has one end anchored, as at Ii. Its swinging end carries a double contact i2 swinging between contacts l3 and II. The contacts I! and M are in ilxel spaced relationship and are mounted on a carrier block II. The carrier block 05 consists .of a nut i5 and arms II and II projecting laterally from the nut, and carries the respective spaced contacts II, II.

The thermally sensitive arm II is connected to a source of electrical current through a lead It. The contacts II and II are connected to the respective iield windings of induction motors 2|, 2|, by leads 22, 22. The motors and 2| may be a single unit consisting of field windings wired to run in opposite directions. A screw threaded shaft 24 is driven by said motors through reduction gearing, as in the issued patent. Bearings 25 are shown diagrammatically for rotatively mounting said shaft. The nut I. of the traveling block II is traversed by the screw threaded portion of the shaft whereby, upon rotation of the shaft, the block will be moved changing the position of the contacts I: and II with respect to the thermally sensitive member ID.

The shaft 24 carries a rotating contact arm 25 making successive contacts with switch segments or poles 21, 2|, 25, and II. This arm 26 and its contacts constitute the sending switch. The shaft 24 also carries a second contact arm 2|, adapted to make successive contact with switch segments or poles 22, 82, II, and 35. The arm II and its contacts constitute the sending switch of the synchronizing system. The contact arm II is of such circumferential dimension, or width of contact portion, that with either direction of rotation in passing from one segment or pole to another, it will always reach a new contact segment or pole before the arm 25 reaches a new contact segment, or pole.

Referring to the receiving or recording unit, the receiving motors are indicated at and ll. These motors II and II are also induction motors having their respective field windings wired to run in oppodte directions. The motor shaft 42 of the receiving or recording unit is provided with a screw threaded section 43, traversing an indicator arm 44. This arm 4| carries a recording instrumentality such as a pen or pencil for, drawing a graph line on a record strip 45, being unreeled from a roll 46, rotating at a uniform rate and driven by some means (not shown) and supported in bearings 41, 41. Shaft 42 also carries two rotating diametrically opposite contact arms 45, 55, respectively connected to the field windings of the motors 4U and-4i bylcads 50, H. A supply lead 52 completes the circuits to the respective motors 20, 2|, l5, and ii.

The rotating contact arms, 49 successively contact segments 53, 54, 55 and 55. These arms l5, l5, and their contacts constitute the receiving switch. Another'rotating contact arm 51, is fixed to the shaft 42 and successively contacts switch segments 58, 55, 60, and ii. The arm 51 and its contacts constitute the receiving switch of the synchronizing system. Corresponding stationary contacts of the respective switches, that is, the sending and receivingof the normal system and the sending and receiving of the synchronizing system, are connected by electrical leads 62.

The contact arms 3i and 51 of the respective sending and receiving switches of the synchronizing system are normally out of step 180. In other words they engage diametrically, opposite contacts of the respective synchronizing switches. Moving contact 51 is connected to the contact ii of the thermally controlled motor control switch by a lead 55 and moving contact 3| is connected to the other contact I of the thermally controlled switch by a lead 66. Thus it is arranged that ii the contacts 2| and 51 get into step, both of the sending motors are then in circuit and the respective fields buck each other which results in looking the coupled reversely wound motors against movement in either direction.

Operation For illustrative purposes, the drawing discloses the system in one of the positions it assumes when at normal rest. As shown, the contact l2 of the thermally sensitive element is out of contact with either contact I! or ll. Now when there is a temperature change in the environment of the sending apparatus, which may be (for the sake of illustration) 9. drop in temperature, it may be assumed that the element Ill swings the contact l2 to the right, engaging the contact I 3. The current then flows through the field of the motor 20 by way of supply line It, contact l2, contact l2, lead 22, the motor winding, and supply line 52. This rotates the shaft 24 and tends to move the contact I3 away from the swinging contact I2 until a break is accomplished; that is until the drop in temperature ceases.

Rotation of the shaft 24 bythe motor 20 moves the switch arm 25 of the sending switch from contact 28 to contact 28. The current then flows from supply line I! through arm 26, contact 29, lead 52, contact arm 49, lead 5|, the winding of induction motor ii, and supply line 52: This rotates the shaft 42 for moving the recording arm in the appropriate direction to indicate the drop in temperature on the recordingsheet.

As soon as the shaft 45 is in rotation, the contact 45 moves from contact 55 to contact 58 which is connected to contact 30 of the sending switch previously dead but now in circuit by virtue of the continued rotation of contact 26 from contact 25 to contact 25. If the drop in temperature continues, the induction motor 2| will continue to run and successive driving impulses will be sent through to the receiver until the contact i3 breaks contact with the swinging contact l2. 3

The reverse direction of rotation occurs in the event of a temperature rise, the induction motor 2| then being placed in circuit by way of supply line l9, contact |2, contact ll, lead 23, the winding of the motor, and supply lead 52. In this event, since the shaft 24 is then reversely driven, contact 26 moves to contact 21, the current then flowing from supply line I! to contact 21, lead 62, contact 53 of the receiving switch, contact arm 48, lead 56, winding 01' the reverse motor 40, and supply line 52. Then the recording arm 64 moves in the opposite direction to record a temperature rise on the recording sheet.

Synchronization ,cuit only in the event of sluggishness or failure o! some sort in the receiving apparatus.

To illustrate the operation of the synchronizing switches, it will be presumed that for some reason the receiving unit becomes inoperative due to the failure of the receiving mechanism or the connections thereto. In this case it is highly desirable also to have the transmitter stop, rather than run ahead of the receiver.

When the contact arm 26 moves from contact 28 to contact 29 the contact arm 3| of the send ing synchronizing switch moves from contact. 35 to contact 32. In fact due to its width, it established this contact with contact 32 before the establishment of contact of arm 26 with contact 29. Assuming the receiver to be inoperative, the contact arm 51 of its synchronizing switch will remain stationary. Now the arm 26 will continue to move along contact 29 while the contact 3| will continue to move along contact 32 until the forward extremity of the arm 3| engages contact 33. Since contact 33 is connected to contact 59, upon which the synchronizing contact arm 51 is resting, this will result in placing the other motor 2| in circuit by way of supply line 52, winding of the motor, lead 66, arm 3|, contact 33, lead 62, contact 59, arm 51, lead 65, contact i3, contact 12, and supply lead i9. Thus the windings of the respective induction motors are both in circuit or in a bucking or balanced condition, and the shaft 24 will then remain stationary. Thus the transmitting end will remain inoperative until the receiving end steps up to its proper position and throws the winding 2| out of circuit.

If the receiver is merely slow in acting, it may stop the transmitter, as described above, but, since it finally moves arm 49 from contact 55 to contact 56, and arm 51 from contact 59 to contact 60, the circuit through to contact 33 and arm 51 will be broken,.de-energizing induction motor 2| whereupon induction motor 20 may continue to run.

In the event that motor 2| was transmitting a temperature rise and the contact 3| of the synchronizing sending switch was moving in a reverse direction, it will, upon engagement with contact 33, connect the supply to contact 59 of the receiving synchronizing switch and will thereupon, ii! the arm 51 has not moved in a normal manner,.connect through it and-lead 65 to the win of the induction motor 20 and supply line 52. This results in energizing both motors andresults in stoppage of the transmission for the same purpose as in the opposite direction previously described.

It is arranged that the system must keep in step or the coupled induction motors of the sendingunit will buck each other and result in a stoppage of-the sending impulses.

Having described my invention, I claim:

1. In a reversible motion transmitting and' synchronizing apparatus, a pair of induction motors wound for reverse direction of rotation respectively, a pole switch driven by said motors controlling a plurality oi controlling circuits, a second electric motor driven switch, the corresponding poles of said motor driven switches respectively in circuit connection, a pilot switch alternately cooperable with oppositely arranged contact elements of said induction motors, a synchronizing switch driven by said induction motors, a second synchronizing switch in driving connection with said second motor driven switch, said synchronizing switches respectively wired for completing the circuit to either one or the other of said induction motors and having their contacts related for energizing the field of the induction motor which is not in operation at the particular time in the event that the second motor driven switch mechanism ceases to operate.

2. In a reversible motion transmitting and synchronizing apparatus, a tour pole sending switch, induction sending motors for operating said four pole sending switch, one for each direction of movement, a control switch for controlling said motors, said control switch operated by said motors when the motors are in motion for automatically breaking contact, a tour pole receiving switch, induction receiving motors controlled by and actuating said four pole receiving switch, the corresponding poles of the sending and receiving switches electrically connected, said receiving motors wound for reverse directions of movement, means driven by said receiving motors, said four pole receiving switch including diametrically opposite contact arms, each electrically connected for controlling a respective receiving motor, and a synchronizing device, including a switch actuated by the sending motors and a switch actuated by the receiving motors, said latter switches including four poles electrically connected, said latter poles corresponding to those of the sending and receiving switches,

- said synchronizing switches having their moving contact arms normally substantially 180 out of step and each connected to a respective directional contact of the control switch for placing both sending motors in circuit when moving contacts of the respective synchronizing switches are in step or engaging corresponding contacts.

3. In a reversible motion transmitting and synchronizing apparatus, a sending switch, induction sending motors for operating said sending switch, one for each direction of movement, a switch for controlling said motors, a receiving switch, induction receiving motors controlled by and actuating said receiving switch, said receiving motors wound for reverse directions of movement, means driven by said receiving motors, said receiving switch including a pair of contact arms, each electrically connected for controlling a respective receiving motor, and a synchronizing device including a switch actuated by the sending motors and a switch actuated by the receiving motors, said switches electrically connected in 111s circuit to the sending motors so as to place both sending motors in circuit upon the feline of the receiving motors to operate thereby causing said motors to buck each other and to remain stationary.

4. A reversible motion transmitting and synchronising apparatus comprising induction motors having reversely wound fields, a pole switch driven by said motors, a pilot switch for enersizing and tie-energizing the induction motors alternately, a second pole switch-said first mentioned pole switch and said second pole switch having their respective corresponding poles connected electrically, receiving motors controlled by said second pole switch, said motors having oppositely wound fields and said pole switch ineluding a control arm for each held, means driven by said receiving motors and a switch controlling electrical circuit for maintaining said pole switches in synchronism, including switches driven by the respective sets of motors having their contacts electrically connected to the respective induction motors but normally out of circuit, said synchronizing switches adapted to place that motor in circuit which is not operating when the pilot switch is in connection for causing the respective motors to buck each other when the receiving motors and apparatus fails to function.

5. A reversible motion transmitting and synchronizing apparatus comprising an electrically braked reversible motor driven shaft, apole switch driven by said shaft, a pilot switch for energising and de-eneigizing the motor, a second pole switch, said first mentioned pole switch and said second pole switch having their respective corresponding poles connected electrically, a receiving reversible motor driven shaft controlled by said second pole switch, and said pole switch including a control arm for each direction of motion means driven by said receiving motor shaft and a switch controlling electrical circuit for maintaining said pole switches in synchronism, including switches driven by the respective motor shafts having their contacts electrically connected to the reversing contacts of the pilot switch but normally out of circuit, said synchronizing switches adapted to place the electrical brake in circuit for locking the first shaft when the receiving apparatus fails to function.

CURTIS P. MITCHELL. 

